The present invention relates to a method of manufacturing a Group II-IV compound semiconductor by a vapor-phase epitaxy and, more in particular, it relates to a method of manufacturing a Group II-IV compound semiconductor suitable to flattening of an epitaxial growth layer and preventing of deposition to a protection film for selective epitaxial growth.
Group II-VI compound semiconductors can oscillate laser covering a short wavelength region from ultraviolet ray to green light ray, as well as a long wavelength region including infrared ray. Recently, it has been succeeded in oscillation of blue laser beam by using a Group II-VI compound semiconductor lattice-matching with a GaAs substrate. Oscillation of the blue laser beam is attained by the formation of quantum well active layers and the improvement of p-type doping technique. However, for controlling a transverse mode, a current constriction structure as used in an AlGaAs-based semiconductor laser is necessary. For forming a block layer to effect a current constriction, application of selective epitaxial growth technique is necessary.
For preparing the quantum well structure, it is necessary to precisely control the epitaxial growth rate and usually, molecular beam epitaxy (MBE) or metal organic vapor phase epitaxy (MOVPE) is conducted. Actually, when the above-mentioned epitaxy method is used, an abrupt hetero boundary is formed at the level of an atom layer. When such a structure is applied to a device, flatness of the hetero boundary has a great effect on device characteristics. Since a migration distance of compound molecules is short in the Group II-VI compound boundary, there is a problem such as worsening of the flatness. While selective epitaxial growth has been conducted in recent years for further optimizing a device structure, since selective epitaxial growth is extremely difficult by the usual MBE method, the MOVPE method or metal organic molecular beam epitaxy (MOMBE) method has been conducted for selective epitaxial growth. Since the selective epitaxial growth is a damageless process carried out at a relatively low temperature, there has a merit capable of obtaining a selective epitaxial growth region of high quality and obtaining a high performance device.
However, in order not to deposit polycrystals on a protection film, upon conducting selective epitaxial growth it is subjected to remarkable restrictions on conditions for vapor-phase epitaxy, crystal mixing ratio and mask width. Particularly, in a case of Zn-containing Group II-VI compound, there has been arisen such a problem that polycrystals are more apt to be deposited on a protection film as the mask width is greater, failing to obtain a desired structure.
As a result of earnest present inventors' studies for solving such a problem, it has been found that use of a halide gas and/or a halogen gas upon forming a heterostructure of a compound semiconductor or upon growing crystals selectively, can flatten the surface of a epitaxial growth layer and enables to conduct a vapor-phase epitaxy of crystals at high quality without depositing polycrystals on a mask over a wide range. On the basis of the finding, the present invention has been accomplished.